Comparison of Overweight Rates in Children Using BMI Versus Waist-to-Height Ratio

Overview

This study compared overweight prevalence in 7,600 UK children using BMI and newly developed waist-to-height ratio (WHtR) cut points. BMI overestimated overweight prevalence by over twofold compared to WHtR, which better identified excess adiposity linked to prediabetes and type 2 diabetes risk.

Background

Childhood overweight and obesity are commonly assessed by BMI, which cannot distinguish fat from muscle mass and varies by age, sex, and ethnicity. Waist-to-height ratio (WHtR) is a sensitive and specific anthropometric measure that better reflects total and central adiposity. Recent guidelines recommend using WHtR alongside BMI for obesity diagnosis. This study validates new pediatric WHtR cut points and compares their classification of overweight and obesity with BMI in a large birth cohort.

Data Highlights

Key Findings

• BMI overestimated overweight prevalence by 2.8-fold in childhood compared to WHtR.
• Among children classified as BMI overweight, 64% had normal fat by WHtR, indicating BMI misclassification.
• Of children with WHtR high fat, 69.8% were BMI overweight and 24% were BMI obese, showing WHtR identifies excess adiposity missed by BMI.
• WHtR high fat category was associated with increased odds of prediabetes (OR 2.36; 95% CI 1.10-5.10).
• WHtR excess fat category was strongly associated with type 2 diabetes risk (OR 6.08; 95% CI 2.84-13.01).
• WHtR provides a cost-effective, accessible, and more accurate method to assess pediatric adiposity than BMI alone.

Clinical Implications

Clinicians should consider incorporating WHtR measurement alongside BMI for more accurate assessment of adiposity in children and adolescents. WHtR better identifies those at risk for metabolic complications such as prediabetes and type 2 diabetes, enabling targeted prevention and management. Given its simplicity and low cost, WHtR can be widely adopted in primary care settings.

Conclusion

WHtR is a superior anthropometric tool compared to BMI for detecting excess adiposity and associated metabolic risk in pediatric populations. Its universal adoption could improve obesity diagnosis and guide effective interventions.

References

1. Agbaje et al. 2024 -- Comparison of Overweight Rates in 7,600 Children Using BMI Versus Waist-to-Height Ratio: Insights from the ALSPAC Study